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Re: Arc length vs pwr



10/25/96

R. Hull wrote: 

>It is very easy to measure charge at a great distance with an 
>electrometer using an isolated isotropic capacitance.  This is how 
>electric field strengths are effectively measured.  The crucial point 
>is that the meter must read only the scalar value of voltage.  

Would you elaborate on "scalar value of voltage"?  Isn't an electric 
field a vector?  What are the other value(s) of voltage?

>This is achieved through the nominal Teraohm input impedance of the 
>avearge professional electrometer. I have an old Cary vibrating reed 
>electrometer with saphire input terminals and gold chambers, and have 
>charged a 20pf vacuum capacitor to 300 volts and left it for two days 
>and the thing still read 300 volts!  The 100% mechanical electrostatic 
>voltmeters are only about 1/100th as sensitive as an electrometer, but 
>still they are about 1000 times more sensitive than a good precision 
>FET VOM or FET digital input meter.
>
>Richard Hull, TCBOR
>

Richard, 

Last week I bought a Model 341 Weston A-C & D-C Voltmeter at a hamfest 
for $15. It is a magnetically sheilded electrodynamometer and indicates 
absolute volts.  In a field of five orsteds it only has a 0.4% fs 
deviation.  I don't know much about this type of meter, but could it be 
used in TC experimentation because of it's magnetic sheilding ability?

Thanks

RWW